CVE-2025-66489 Cal.com Authentication Bypass via bad TOTP + password checks

Critical 9.9 Published 3 Dec 2025 Updated 3 Dec 2025

Attackers can bypass password verification by providing a TOTP code, gaining unauthorized access to user accounts in Cal.com.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2025-66489?

CVE-2025-66489 is a critical authentication bypass vulnerability in calcom cal.com, published on 3 Dec 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

Cal.com is open-source scheduling software. Prior to 5.9.8, A flaw in the login credentials provider allows an attacker to bypass password verification when a TOTP code is provided, potentially gaining unauthorized access to user accounts. This issue exists due to problematic conditional logic in the authentication flow. This vulnerability is fixed in 5.9.8.

Weakness: CWE-303

Which versions are affected by CVE-2025-66489?

It affects 1 product.

Products include Cal Cal.com.

How do I fix CVE-2025-66489?

No fix has been published for CVE-2025-66489 yet. Limit exposure of the affected software until one is available.

Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.

Is CVE-2025-66489 being exploited?

There is no known exploitation of CVE-2025-66489 in the wild and no public exploit code.

Sources

Also known as GHSA-9r3w-4j8q-pw98.